Small hole gauge



Aug. 29, 1944- J. A. DIETRICH SMALL HOLE GAUGE Filed Jan. 23, 1945 M h,M n M Patented Aug. 29, 1944 zssassz sNALL HOLE GAUGE John A. Dietrich,Peoria, Ill. Application January 28, 1943, Serial Nb. 473,367

(01. ss 17s) 4 Claims.

This invention relates to a small hole gauge, and it is an object of theinvention to provide an instrument of this kind embodying the use of arecording needle made in one piece to assure an accurate reading, andalso to prolong the life of the instrument.

It is also an object of the invention to provide an instrument of thiskind which embodies a three-point locating means and wherein certain ofsaid points are adjustable to allow the gauge to beset to a desired sizeas initially determined by use of a ring gauge.

The invention consists in the details of construction and in thecombination and arrangement of the several parts of my improved smallhole gauge whereby certain important advantages are attained, as will behereinafter more fully set forth.

In order that the invention may be the better understood, I will nowproceed to describe the same with reference to the accompanying drawing,wherein Figure 1 is a view in side elevation of a small hole gageconstructed in accordance with an embodiment of my invention;

Figure 2 is a view in front elevation of the device as herein comprised;and

Figure 3 is an enlarged detail sectional view taken substantially on theline 3-3 of Figure 1.

The gauge as herein disclosed comp-rises a cylindrical body member l ofdesired dimensions and which is provided with a longitudinally disposedand radially arranged slot 2 open at the rear end of the body I. Thebase or intermediate wall a of the slot is disposed inwardly anddownwardly on a predetermined curvature with the larger end of the slotopening through the rear end of the body I. This slot 2 also opensthrough the periphery of the body I and extends substantially the entirelength thereof but terminates slightly inwardly of the front end of thebody member I.

Within the forward or smaller end of the slot 2 is received thesemi-circular forward portion 3 of a substantially fiat head H, andwhich head H is mounted upon a pin 4 disposed laterally through theforward portion of the body I and intersecting the adjacent portion ofthe slot 2. The semi-circular portion 3 is concentric to the axisafforded by the pin 4.

The head H is provided with an upwardly or inwardly disposed enlargement5 providing a forwardly facing shoulder 6 radially disposed with respectto the axis upon which the head H rocks, and bearing against thisshoulder 6 is an expansible spring I. 'I'hisspring l extends within anopening 8 in the outer or front end of the body I and communicating-withthe forward portion of the slot 2. The inserted endof the applied springI contacts with a plug 9 threading in the outer portion of the opening'8 whereby the spring I is effectually maintained inworking position andwhereby the tension of the spring, when desired, may be regulated.

The lower portion of the head H slightly inwardly of its axis ofrotation is provided with a depending or outwardly directed ear or lugI0 substantially semi-circular in form and which is of such radius as toextend outwardly beyond the periphery of the body I. The head H isintegrally formed with an elongated needle or pointer H, said head H andpointer or needle ll being coplanar. This needle or pointer H is ofdesired length and extends out beyond the rear open end of the slot 2for ooact'ion with the graduations l2 provided on a faceof a rearwardlydirected fiat plate 14. This plate Id, at its inner portion and for amajor part of. its length, is of a Width substantially equal to thediameter of the member l and is positioned immediately to one side ofthe slot 2 so that the pointer or needle M will be positioned formovement across and immediately adjacent to the plate 14. The outer orfree extremity or end portion I5 of the plate [4 is laterally ortransversely enlarged to allow for the application of the desiredgraduations E2.

The graduations [2 indicate thousandths of an inch at opposite sides ofthe intermediate zero point. The rear portion of the slot 2 closelyadjacent to the periphery of the body l through which the slot opens isintersected by a stop pin 16, While the same end portion of the slot 2at a point inwardly of the pin it is intersected by a second stop pin llwhereby the extent of swinging movement of the pointer or needle H ineither direction beyond the zero graduation is limited. These pins I6and H are properly inserted through the inner or rear portion of thebody l.

The forward or outer end portion of the body I is provided in itsperiphery with theinwardly converging openings l8. These openings B8 areradially arranged with respect to the axial center of the body I and areso angularly related to have their outer ends equi-distantly spaced fromthe face of the slot 2 opening through the periphery of the body I andfrom each other. Threading into these openings l8 are the elongatedscrews l9, the extent of projection of these screws I9 beyond theperiphery of the body I being selectively set upon proper turningmovement of the screws [9.

In practice, the outer ends of the screws l9 and the lug l provide athree-point location means, and initially the screws [9 are set by theuse of a ring gauge as determined by the desired size. When the screwsare properly set the pointer or needle II will be at the zero or neutralpoint of the graduations l2 and when the instrument is inserted withinthe opening to be gauged, if such opening should be .00 5 smaller thanthe desired size this will be readily denoted by the proper indicationon the plate I4 on the minus side of the zero or neutral indication,while, of course, if the opening be too large the same will be indicatedby the pointer or needle coacting with the proper graduation on the plusside.

While it is not desired to limit the invention to any particular use, itis to'be stated that it is especially designed for gauging small holes.

From the foregoing description it is thought to be obvious that a smallhole gauge constructed in accordance with my invention is partiucuarlywell adapted for use by reason of the convenience and facility withwhich it may be assembled and operated.

I claim:

1. An inside diameter gauge comprising a cylindrical body having aradial slot opening through one end of the body and through the sidethereof, a plate extending from the said end end of the body at one sideof the slot, a scale carried by the plate upon the side nearest theslot, a needle extending longitudinally of the said side of the plateand having an end extended into and to the other end of the slot, saidend of the needle having a lug extending outwardly from the slot beyondthe side of the cylinder, means extending across the slot and throughthe said end of the needle upon the side of the lug remote from theother end of the needle and pivotally supporting the needle across assaethe plate, and resilient means interposed between a wall of the slot andthe said end of the needle upon the opposite side of the pivot meansfrom the lug and resiliently opposing pivotal movement of the needle inone direction across the plate and scale.

2. An inside diameter gauge as set forth in claim 1, with a pair ofmembers threaded into the cylindrical body in a plane transversely ofthe body of said lug, said members and the lug being equi-distantlyspaced around the body.

3. An inside diameter gauge comprising a cylindrical body having aradial slot opening through one end thereof and through the side, aplate extending from the said one end of the body at one side of theslot, a pivot pin extending transversely of the slot adjacent the otherend and in relatively close proximity to the outer side of the slot, ascale across the side of the plate nearest the slot, a needle having aflat head at one end disposed within the slot and traversed by saidpivot pin for the oscillation of the needle on the pin, the other end ofthe needle being adjacent said scale, a lug forming an integralextension of the head of the needle between the pivot pin and the pointof the needle and projecting from the slot beyond the side of the body,the head upon the opposite side of the pivot pin from the lug beingformed to provide a shoulder facing in the opposite direction from thepoint of the needle and opposed to a wall of the slot, an expansionspring between said shoulder and the said wall of the slot to normallyurge oscillation of the needle in one direction, and means for limitingthe oscillation of the needle in the slot.

4. An inside diameter gauge as set forth in claim 3 with two pinsthreaded radially into the cylindrical body and disposed in the sameplane transversely of the body as said lug, the pins being radiallyadjustable and the pins and lug being equi-distantly spaced around thebody.

JOHN A. DIETRICI-l.

